Casing construction

ABSTRACT

An improved vapor generator roof construction of the type having an inner and outer casing and support rods extending therethrough and welded to the inner casing with the outer casing being formed of flanged openings and plates cooperating with one another to accommodate movement of the rods due to thermal expansion and contraction of the inner casing independent of the outer casing.

United States Patent [191 Piaskowski Nov. 26, 1974 [54] CASING CONSTRUCTION 3,229,672 H1966 Mirigay 122 510 [75] Inventor: Edward J. Piaskowski, Massillon, i T g 122 M9 4 Ohio p [73] Assignee: The Babcock & Wilcox Company, imary i e enn Sprague New York, NY. Attorney, Agent, or Firm-Joseph M. Maguire, Esq.; [22] Filed: Dec 1973 Robert J. Edwards, Esq.

[21] Appl. No.: 424,144 [57] ABSTRACT An improved vapor generator roof construction of the [52] US. Cl. [22/494, 122/510 yp having an inner and Outer casing and pp [51] Int. Cl F22b 37/36 rods extending therethrough a d e d to he nner [58] Field of Search 122/235 R, 235 G, 494, ing with the Outer casing being formed of flanged 122/510 openings and plates cooperating with one another to V accommodate movement of the rods due to thermal [56] Referen Cit d expansion and contraction of the inner casing inde- UNITED STATES PATENTS pendent of the outer casing.

2,337,208 12/1943 Reintjes 122/235 x 8 Claims, 7 Drawing Figures rr-n 1 4.4 56 l CASING CONSTRUCTION BACKGROUND OF THE INVENTION This invention relates generally to a top-supported vapor generator of the type having a roof formed of an inner and outer casing and, particularly, to an improved roof construction whereby the outer casing is independent of the movement of the inner casing resulting from thermal expansion and contraction.

The vapor generator setting includes a gas pass enclosure comprising a furnace chamber, convection and outlet gas passes, associated boundary walls and a compartment commonly referred to as the penthouse which is situated on top of the gas pass enclosure and is separated therefrom by a substantially gastight partition wall. The gas pass enclosure includes convection heating surfaces such as a superheater, reheater and economizer which may have tube ends extending through the partition wall and into the penthouse for flow connection to headers. The supporting structure associated with the vapor generator includes support rods which attach to the aforementioned headers and extend through the roof of the unit which also functions as the penthouse roof.

The roof is formed of an inner and outer casing vertically spaced from one another and including insulation disposed therebetween. The support members or rods which extend through the roof are rigidly connected to of the inner casing. Passageways are formed between the base flanges to promote drainage of water from the sloped roof.

BRIEF DESCRIPTION OF THE DRAWINGS raised portions formed along the outer casing portion the inner casing and more with it as it undergoes thermal expansion and contraction whenever the unit is placed into or removed from service. However, a problem arises with respect to the movement of the support rods relative the outer casing since the latter experiences virtually no expansion or contraction due its exposure to ambient temperature and its insulation from the heat of the penthouse.

Prior art efforts at dealing with this problem have not been altogether satisfactory. One approach has been to manufacture the outer casing from light gauge metal and to employ sliding seams and box type expansion folds to accommodate fore-and-aft and side-to-side movement of the support rods due to thermal expansion and contraction of the inner casing. Seals at the rods consist of cans screwed to the casing with caulking at the joint and also at the point of rod penetration. This arrangement has been particularly troublesome on outdoor installations with water seepage taking place at the seam and joints. .The water quenches the inner casing thereby causing severe metal buckling and eventual failure.

SUMMARY OF THE INVENTION In accordance with the present invention there is provided a novel construction whereby the outer casing is not fastened to the inner casing, and does not use sliding scams or expansion joints. The present outer casing includes a base formed with side-to-side and peripheral openings to accommodate passage therethrough of the support rod rows. The openings are bordered with upturned flanges and are covered by flanged pans which are spaced to accommodate passage therebetween of individual support rods. Flanged plates are welded to each rod to cover the space between pans. The flanged base, pans and plates have their respective flanges cooperatively associated to provide a water tight outer casing capable of accommodating the movement of the support rods due to thermal expansion and contraction of the roof.

FIG. 6 is an enlarged detail of a typical outer casing tie along the roof side-to-side axis of zero expansion.

FIG. 7 is an enlarged detail of a typical outer casing stop along the roof fore-and-aft axis of zero expansion.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, the invention has been illustrated as embodied in a top-supported forced flow once-through vapor generator intended for central station use.

The unit, as depicted in FIG. 1, comprises a setting 10 having a gas passageway situated therein and including a furnace chamber 12 whose upper end opens for discharge into a horizontal gas passage 14 with the latter, in turn, discharging into a down flow or convection gas passage 16. The setting 10 includes an upper chamber or penthouse 18 disposed above the furnace chamber 12 and the gas passages 14 and 16, and isolated therefrom by a substantially gastight partition wall 20.

The penthouse 18 extends upwardly from the partition wall 20 and laterally beyond the furnace and gas passage boundary walls to form an insulated chamber for housing headers, tubes and piping associated with the vapor generator. The roof 22 over the setting 10, which also serves as the penthouse roof, accommodates the passage therethrough of a plurality of upright members or rods 24 used to supportingly connect the vapor generator to cross beams 26, the latter being part of the structural steel work which includes upright columns 28 transmitting the weight load of the vapor generator to ground G.

The furnace chamber 12 is formed with a sloped bottom which includes a discharge opening 30 communicating with an ash hopper 32 disposed thereunder and ground supported by a plurality of stanchions 34. The fuel firing equipment comprises independently operable fuel burners (not shown) extending horizontally along the center line of respective burner ports 36 located on the rear and front walls at the lower portion of furnace chamber 12. I

The gas passage 14 contains a secondary superheater 38 and a reheater 40 arranged in series with respect to gas flow. The gas passage 16 contains a primary superheater 42 having two banks also arranged in series with respect to gas flow.

The penthouse 18 is shown as housing the furnace front wall upper header 44, the secondary superheater inlet and outlet headers 46 and 48, respectively, the reheater outlet and inlet headers 50 and 52, respectively,

the primary superheater outlet header 54 and the convection gas pass rear wall header 56. it should be understood that the penthouse normally houses numerous other headers as well as tube sections and piping, these were omitted from FIG. 1 so as not to encumber the illustration.

In FIG. 2 there is shown a plan view of the roof 22 depicting the outer casing or covering 58 which normally consists of heavy gauge sheet metal (12 ga. minimum), and includes a base portion 60, the latter being formed by the joining together of flat rectangular plates, preferably by seal-welding at the seams 62. The outer casing 58 is anchored along the roof fore-and-aft line of zero expansion XX through a series stop-bars 64, and along the roof side-to-side line of zero expansion YY through a series of tie-bars 66. The base portion 60 is provided with a plurality of elongated openings 68 of generally rectangular configuration and which accommodate the passage therethrough of the upright members 24. The base portion sides which define each of the elongated openings 68 are formed with upturned flanges 70. A plurality of spaced raised portions 72 are situated above each of the openings 68 and rest on the flanges 70 associated therewith. The dimensions of the openings 68, the spacing of the flanges 70 and the raised portions 72 are all predetermined to accommodate passage therebetween of the upright support members 24 while providing the necessary clearance for the movement of the members 24 due to expansion and contraction of the inner casing 76, shown in FIG. 3. Each of the upright members 24 is fitted with a flat rectangularly-shaped plate 74 which serves to cover the spacing between raised portions 72. The roof 22 is sloped, with the decline being preferably directed toward the rear of the unit, to promote water drainage along the passageways 75 which are between the flanges 70 of adjacent openings 68 on the base portion 60. The openings 68 are normally arranged in either a side-to-side or fore-and-aft direction with respect to the unit, however, itshould be understood that the openings 68 may also extend in an oblique direction.

In FIGS. 3 and 4 there are shown details embodying the present invention and including the outer casing 58 comprising, the base portion 60 formed with elongated openings 68 and spaced raised portions 72 disposed there-above and resting on flanges 70. The upright support members 24 extend through the inner casing or covering 76 and the openings 68 between the flanges 70 and through the space between raised portions 72. The upright members 24 are preferably seal-welded to the inner casing 76. The space between the inner casing 76 and the base portion 60 of the outer casing 58 is filled with rigid insulation 78, eg calcium silicate block insulation whereas the space between the flanges 70 and the raised portions 72 is filled with compressible insulation 80, e.g., blanket type insulation. Each of the raised portions 72 is preferably of elongated rectangu lar configuration and has its elongated sides overlapping the adjoining flanges 70 and formed with downturned flanges 82 which terminate at a level intermediate the height of the flanges 70. The remaining sides of the raised portion 72 are formed with upturned flanges 84. Each upright member 24 includes a plate 74 welded thereto and sized to overlap the adjoining flanges 70 and the raised portions 72. The overlapping ends of plate 24 are formed with downturned flanges 86 which cooperate with the adjoining flanges 82 and 84 to form a substantially watertight slidable joint therebetween. Water collecting on the outer casing 58 is drained therefrom along the passageways 75.

In FIG. 5 there is shown a perspective view of a portion of the outer casing 58 including the base portion 60 formed with flanges 70 bordering the opening 68, the latter being covered by the combination of raised portions 72 and plates 74. The raised portions 72 are spaced apart to provide for passage therebetween of the upright members 24. The flanges 82, 84 and 86 cooperate with one another to enable the outer casing portions 60 and 72 and plates 74 to form a watertight cover capable of accommodating the movement of the upright members 24 resulting from thermal expansion and contraction of the inner casing.

FIG. 6 illustrates a typical outer casing tie at the roof side-to-side line of zero expansion YY including a pair of tie-bars 66 straddling the upright member 24 and joining together the base portion 60 across the opening 68. The tie-bars 66 are welded to the oppositely faced sides of flanges 70 at the level of the base portion 60.

FIG. 7 illustrates a typical outer casing stop at the roof fore-and-aft line of zero expansion XX including a pair of stop-bars 64 abutting the upright member 24. The stop-bars 64 are welded to the oppositely faced sides of flanges 70 and project toward one another across the opening 68 at the level of the base portion 60.

During operation of the vapor generator, the inner casing 76 may attain temperatures of 500 to 800F while the outer casing 58 remains at or near ambient temperature. As the unit is brought up to operating capacity or while it is being shut down, the inner casing metal will experience thermal expansion or contraction, as the case may be, from the anchoring points lying along the axes XX and YY which normally coincide with the fore-and-aft and side-to-side centerlines of the unit. The support rods 24 move with the expansion and contraction of the inner casing 76 with this movement being accommodated within the outer casing openings 68 and between the raised portions 72 which are spaced from one another and are also free to slide along the base flanges 70. The space between raised portions is covered by the plates 74 which move with the rods 24.

While in accordance with the provisions of the statutes there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresonding use of the other features.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In combination with a vapor generator, structure defining a setting, a gas passageway situated within said setting, means for introducing combustion gases through said passageway, the setting having a roof formed of spaced first and second metal coverings, the first covering being disposed subjacent to the second covering and the space therebetween being at least partly filled with an insulating material, at least one upright member extending throuugh said roof, the upright member being rigidly connected to said first covering,

the improvement comprising means allowing thermal expansion and contraction of said first covering and upright member independent of the second covering, said last named means including having the second covering formed of a base portion having at least one elongated opening of generally rectangular configuration, the base portion including an upturned flange projecting from each of the sides defining said opening, at least two coplanar raised portions disposed above said flanges, said raised portions being spaced from one another, and said upright member extending between the flanges and raised portions in spaced relation thereto, plate means disposed above the raised portions and including an opening to accommodate passage therethrough of the upright member, said plate means being rigidly connected to the upright member and cooperating therewith and with the raised portions to cover said elongated opening.

2. The combination according to claim 1 wherein the roof is sloped.

3. The combination according to claim 1 wherein at least some of the ends of said raised portions overlap the flanges situated adjacent thereto.

4. The combination according to claim 3 wherein each of the overlapping ends is formed with a downtumed flange.

5. The combination according to claim 4 wherein each of the downtumed flanges is laterally spaced from the adjacent upturned flange and terminates at a level intermediate the height thereof.

6. The combination according to claim 1 wherein oppositely adjacent ends of said raised portions are formed with upturned flanges.

7. The combination according to claim 1 wherein ends of the plate means overlap said raised portions.

8. The combination according to claim 7 wherein each of the overlapping ends is formed with a downtumed flange. 

1. In combination with a vapor generator, structure defining a setting, a gas passageway situated within said setting, means for introducing combustion gases through said passageway, the setting having a roof formed of spaced first and second metal coverings, the first covering being disposed subjacent to the second covering and the space therebetween being at least partly filled with an insulating material, at least one upright member extending through said roof, the upright member being rigidly connected to said first covering, the improvement comprising means allowing thermal expansion and contraction of said first covering and upright member independent of the second covering, said last named means including having the second covering formed of a base portion having at least one elongated opening of generally rectangular configuration, the base portion including an upturned flange projecting from each of the sides defining said opening, at least two coplanar raised portions disposed above said flanges, said raised portions being spaced from one another, and said upright member extending between the flanges and raised portions in spaced relation thereto, plate means disposed above the raised portions and including an opening to accommodate passage therethrough of the upright member, said plate means being rigidly connected to the upright member and cooperating therewith and with the raised portions to cover said elongated opening.
 2. The combination according to claim 1 wherein the roof is sloped.
 3. The combination according to claim 1 wherein at least some of the ends of said raised portions overlap the flanges situated adjacent thereto.
 4. The combination according to claim 3 wherein each of the overlapping ends is formed with a downturned flange.
 5. The combination according to claim 4 wherein each of the downturned flanges is laterally spaced from the adjacent upturned flange and terminates at a level intermediate the height thereof.
 6. The combination according to claim 1 wherein oppositely adjacent ends of said raised portions are formed with upturned flanges.
 7. The combination according to claim 1 wherein ends of the plate means overlap said raised portions.
 8. The combination according to claim 7 wherein each of the overlapping ends is formed with a downturned flange. 